376 BOTANICAL GAZETTE [May 
varying with the conditions under which the buds are induced to 
develop and the general health of the tree at the time” (p. 157); 
the greater the supply of nutriment, the more likely it is that the 
proliferating branch will produce spurs, the primordial foliage 
occurring on those with the smaller supply. BortHwick has even 
referred to an economic aspect of the proliferation of the spur. 
He considers that the appearance of scraggy pine trees could be 
improved by a judicious disbudding process and a stimulation of 
the spurs to form branches. 
It is in the seedling and in the young vigorous plant that I have 
observed most instances of proliferation, the occurrence of prolif- 
erating spurs following very closely that of supernumerary needles. 
This applies also to their common production in the mature tree 
by wounding. 
The upper part of a seedling of P. Strobus at the beginning of 
its third year is shown in fig. 6. A branch with young spur shoots 
(this season’s growth) has been developed from the interfoliar buds 
of four spur shoots of last season’s growth. The central one of 
these will probably form the future stem. The big branch to the 
lower right of the photograph, whose leaves have been tied together, 
arose a year previously also from a spur. Above it is a normal 
fascicle which has not proliferated. The main axis below the leafy 
part had its end destroyed, as its dead stump shown against the 
small white slip indicates. Its lower branches, which were unll- 
jured, bore only normal spur shoots, and it is possible that wound- 
ing has had something to do with the proliferation of the upper 
spurs. I found, however, in what so far as could be determined 
was an uninjured sister plant, one case of proliferation. In another, 
also apparently uninjured, I found a reversion to primordial leaves, 
which has been previously mentioned; though the large branch 
shown to the upper left of fig. 11 did not arise from a spurt shoot, 
at least, if it did, no trace of the fascicle of leaves remains, yet to the 
right of the terminal bud there is a spur shoot with a small set of 
primordial leaves, while to the lower left of the figure two other 
fascicles are shown with smaller series, so small that they are prac” 
tically green buds. This photograph was taken while: the plant 
was in its winter condition. Two of these fascicles have since 
